Diurnal rhythmicity of absorption of a lipid compound (vitamin K-1)in vivo in the rat

1978 ◽  
Vol 23 (12) ◽  
pp. 1125-1128 ◽  
Author(s):  
Daniel Hollander ◽  
Michael Kielb ◽  
Elena Rim
Keyword(s):  
Vitamin K ◽  
Diurnal Rhythmicity

Vitamin K promotes mineralization, osteoblast-to-osteocyte transition, and an anticatabolic phenotype by γ-carboxylation-dependent and -independent mechanisms

2009 ◽  
Vol 297 (6) ◽  
pp. C1358-C1367 ◽  
Author(s):  
Gerald J. Atkins ◽  
Katie J. Welldon ◽  
Asiri R. Wijenayaka ◽  
Lynda F. Bonewald ◽  
David M. Findlay
Keyword(s):  
Bone Formation ◽  
Vitamin K ◽  
Type I Collagen ◽  
Vitamin K2 ◽  
Type I ◽  
Vitamin K1 ◽  
Vitamin K3 ◽  
Positive Effect

The vitamin K family members phylloquinone (vitamin K1) and the menaquinones (vitamin K2) are under study for their roles in bone metabolism and as potential therapeutic agents for skeletal diseases. We have investigated the effects of two naturally occurring homologs, phytonadione (vitamin K1) and menatetrenone (vitamin K2), and those of the synthetic vitamin K, menadione (vitamin K3), on human primary osteoblasts. All homologs promoted in vitro mineralization by these cells. Vitamin K1-induced mineralization was highly sensitive to warfarin, whereas that induced by vitamins K2 and K3 was less sensitive, implying that γ-carboxylation and other mechanisms, possibly genomic actions through activation of the steroid xenobiotic receptor, are involved in the effect. The positive effect on mineralization was associated with decreased matrix synthesis, evidenced by a decrease from control in expression of type I collagen mRNA, implying a maturational effect. Incubation in the presence of vitamin K2 or K3 in a three-dimensional type I collagen gel culture system resulted in increased numbers of cells with elongated cytoplasmic processes resembling osteocytes. This effect was not warfarin sensitive. Addition of calcein to vitamin K-treated cells revealed vitamin K-dependent deposition of mineral associated with cell processes. These effects are consistent with vitamin K promoting the osteoblast-to-osteocyte transition in humans. To test whether vitamin K may also act on mature osteocytes, we tested the effects of vitamin K on MLO-Y4 cells. Vitamin K reduced receptor activator of NF-κB ligand expression relative to osteoprotegerin by MLO-Y4 cells, an effect also seen in human cultures. Together, our findings suggest that vitamin K promotes the osteoblast-to-osteocyte transition, at the same time decreasing the osteoclastogenic potential of these cells. These may be mechanisms by which vitamin K optimizes bone formation and integrity in vivo and may help explain the net positive effect of vitamin K on bone formation.

VKORC1 deficiency in mice causes early postnatal lethality due to severe bleeding

2009 ◽  
Vol 101 (06) ◽  
pp. 1044-1050 ◽  
Author(s):  
Gabriele Spohn ◽  
Andre Kleinridders ◽  
F. Thomas Wunderlich ◽  
Matthias Watzka ◽  
Frank Zaucke ◽  
...  
Keyword(s):  
Vitamin K ◽  
Knockout Mice ◽  
Severe Bleeding ◽  
Clotting Factors ◽  
Vitamin K Cycle ◽  
Severe Deficiency ◽  
Epoxide Reductase ◽  
Bone Calcification

SummaryVitamin K hydroquinone is oxidised to the epoxide form (K>O) during vitamin K-dependent posttranslational γ-glutamyl carboxylation resulting in biological active so called vitamin K-dependent proteins. In turn, K>O is reduced by the enzyme VKORC1 (vitamin K epoxide reductase complex component 1) to complete the vitamin K cycle. To investigate the biological role of VKORC1 in vivo, we generated VKORC1 knockout mice. Homozygous VKORC1-deficient mice developed normally until birth. Within 2–20 days after birth, the knockout mice died due to extensive, predominantly intracerebral haemorrhage. Bleeding resulted from a severe deficiency of γ-carboxylated clotting factors. This lethal phenotype could be rescued by oral administration of vitamin K. Additionally, morphometric analysis of the limbs in VKORC1-deficient animals revealed reduced length of bone calcification relative to wild-type control mice. The observed phenotype of VKORC1 knockout mice excludes the existence of other enzymes with VKOR activity that can substitute to supply vitamin K hydroquinone required for maturation of blood clotting factors. Thus, our study underscores the essential role of VKORC1 in vitamin K-dependent γ-glutamyl carboxylation.

Comparison of rat liver response to coumarin administered in vivo versus in vitro

1964 ◽  
Vol 206 (1) ◽  
pp. 229-238 ◽  
Author(s):  
Judith G. Pool ◽  
C. F. Borchgrevink
Keyword(s):  
Amino Acid ◽  
Oxidative Phosphorylation ◽  
Vitamin K ◽  
Inhibitory Effect ◽  
Factor Vii ◽  
General Effect ◽  
Liver Slices ◽  
Cell Energy

Warfarin added to incubated liver slices inhibits the synthesis of factor VII (proconvertin) in proportion to the log of its concentration; surprisingly, it has the same inhibitory effect on the transport and incorporation of amino acid into protein of the liver slices. This latter finding seems to support the frequently proposed concept that vitamin K has a role in oxidative phosphorylation and that coumarin compounds, by antagonizing vitamin K, uncouple oxidative phosphorylation and thus have a general effect on cell energy supply. However, when we studied the liver of rats depleted of vitamin K the same effect was not seen. Liver slices from such animals produced little factor VII but they incorporated amino acid at the normal rate. Furthermore, administration of warfarin in vivo had the same result as vitamin K depletion: a fall in circulating prothrombin complex but no decrease in either labeling of plasma proteins by intravenous C14-amino acid or incorporation of amino acid into subsequently excised liver slices. There is thus a striking discrepancy between the action of warfarin administered in vitro and that administered in vivo.

The In Vivo Effects of Oral Anticoagulants in Man: Comparison Between Liver and Non-Hepatic Tissues

1988 ◽  
Vol 59 (02) ◽  
pp. 147-150 ◽  
Author(s):  
Marian de Boer-van den Berg ◽  
Henk H W Thijssen ◽  
Cees Vermeer
Keyword(s):  
Vitamin K ◽  
Reductase Activity ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Quinone Reductase ◽  
Hepatic Microsomes ◽  
Precursor Proteins ◽  
Epoxide Reductase ◽  
In Vivo Effects

SummaryThe in vivo effects of oral anticoagulant therapy with 4–hydroxycoumarins on various vitamin K–dependent enzyme systems in man were compared. In hepatic microsomes obtained from donors who has been treated with 4–hydroxycoumarins for more than 6 months, the vitamin K 2,3 epoxide reductase activity and the DTT–dependent vitamin K quinone reductase activity were diminished to 35% and 20% of the corresponding normal values. In the non–hepatic tissues, only a small decrease in vitamin K 2,3 epoxide reductase activity could be demonstrated, while no differences were found in the vitamin K quinone reductase activities. In none of the tissues a significant increase of non–carboxylated precursor proteins was observed, whereas also vitamin K hydroquinone–dependent carboxylase activities seemed to be unaffected by the anticoagulant treatment.

scholarly journals Protein C, an antithrombotic protein, is reduced in hospitalized patients with intravascular coagulation

Blood ◽  
1982 ◽  
Vol 60 (1) ◽  
pp. 261-264 ◽  
Author(s):  
JH Griffin ◽  
DF Mosher ◽  
TS Zimmerman ◽  
AJ Kleiss
Keyword(s):  
Liver Disease ◽  
Serine Protease ◽  
Vitamin K ◽  
Protein C ◽  
Activated Protein C ◽  
Coagulation System ◽  
Antigen Concentration ◽  
Intravascular Coagulation ◽  
The Mean

Abstract Activated protein C is a potent anticoagulant and profibrinolytic enzyme that can be derived from the vitamin-K-dependent serine protease zymogen, protein C, by the action of thrombin. Protein C antigen concentration was determined in plasmas from normals (n = 40) and from 38 patients with intravascular coagulation as evidenced by positive FDP (greater than micrograms/ml). Plasma protein C was 4 micrograms/ml in normals and was significantly depressed (less than 2 SD below the mean of normals) in 19 of the 38 patients. Of 15 patients with suspected intravascular coagulation but normal FDP, protein C was decreased in 5 individuals; 3 of these 5 patients had liver disease. Based on these results, we suggest that extensive activation of the coagulation system in vivo causes a significant consumption of protein C, presumably due to its activation by thrombin and subsequent clearance.

Vitamin K2 colonic and ileal in vivo absorption: bile, fatty acids, and pH effects on transport.

1977 ◽  
Vol 233 (2) ◽  
pp. E124 ◽  
Author(s):  
D Hollander ◽  
E Rim ◽  
P E Ruble
Keyword(s):  
Fatty Acids ◽  
Bile Salt ◽  
Vitamin K ◽  
Salt Concentration ◽  
Absorption Rate ◽  
Vitamin K2 ◽  
Dietary Vitamin ◽  
Hydrogen Ion Concentration ◽  
Bile Salt Concentration

Colonic and ileal absorption of vitamin K2 ([2-methyl-3H]menaquinone-9) was investigated in the conscious rat. When the absorption rate was plotted against the perfusate concentration, a linear relationship was found between these two parameters in the ileum and colon. The absorption rate of menaquinone by the ileum was increased as the bile salt concentration, degree of unsaturation of the added long-chain fatty acids, hydrogen ion concentration, and perfusate flow rates were increased. Colonic menaquinone absorption decreased as the bile salt concentration was increased. Menaquinone colonic absoprtion increased as the pH decreased, but no change was noted as the perfusion rate was increased. The present experimental observations in vivo, coupled with prior observations in vitro, indicate that absorption of menaquinone by the ileum and colon occurs by a passive diffusion process that is modified by variations in the perfusate bile salt concentration, the presence of unsaturated fatty acids, and the perfusate pH. The present observations indicate that the mammalian colon and terminal ileum can provide a constant source of vitamin K to aid hemostasis despite episodic lack of dietary vitamin K.

scholarly journals A cellular system for quantitation of vitamin K cycle activity: structure-activity effects on vitamin K antagonism by warfarin metabolites

Blood ◽  
2014 ◽  
Vol 123 (4) ◽  
pp. 582-589 ◽  
Author(s):  
Jamil A. Haque ◽  
Matthew G. McDonald ◽  
John D. Kulman ◽  
Allan E. Rettie
Keyword(s):  
Vitamin K ◽  
Activity Analysis ◽  
Factor Ix ◽  
Hek 293 ◽  
Vitamin K Cycle ◽  
Structure Activity ◽  
Activity Structure ◽  
293 Cells ◽  
Key Points

Key Points Factor IX glutamyl carboxylation in engineered HEK 293 cells recapitulates in vivo anticoagulant inhibition of vitamin K cycle activity. Warfarin metabolite structure-activity analysis on vitamin K cycle antagonism determines their contributions to in vivo anticoagulation.

VKORc1 Is Under-Expressed in Skeletal Muscle of Humans, Dogs and Mice: Potential Implications for Ectopic Coagulation Factor Expression in Pre-Clinical and Therapeutic Applications

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1477-1477
Author(s):  
Courtney T Connolly ◽  
Armida Faella ◽  
Timothy C. Nichols ◽  
Katherine A. High ◽  
Valder R. Arruda ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Vitamin K ◽  
Specific Activity ◽  
Coagulation Factor ◽  
Factor Ix ◽  
Biologically Active ◽  
Transcript Levels ◽  
Vitamin K Cycle

Abstract Post-translational modifications of coagulation factors in the liver are essential for function. The vitamin K dependent coagulation proteins (VKCPs) require vitamin K to undergo gamma carboxylation of the glutamic residues in their Gla domain by gamma-glutamyl carboxylase [GGCX]. The vitamin K is then recycled by the action of epoxide reductase [VKORc1] and/or quinone reductase [NQO1]. The hemostatic importance of the vitamin K “cycle” is evidenced by patients who may suffer bleeding complications when anticoagulated with warfarin, which targets the vitamin K cycle. Moreover, the ability of a variety of VKCPs to secrete a biologically active product depends on the removal of their propeptide by the action of the intracellular endoprotease furin [FURIN gene]. Previous in vitro work on recombinant coagulation Factor IX, which is used for hemophilia B treatment, has connected these two processing steps by showing that endogenous VKORc1 as well as FURIN can be limiting factors in high-yield expression systems. In vivo, skeletal muscle (in contrast to liver) has been utilized to express low levels of coagulation Factor IX in the first hemophilia B gene therapy clinical trial. However, our experiments in mice demonstrated that the specific activity of muscle-synthesized Factor IX via gene transfer decreased at the high levels of FIX expression by a limited muscle area (Schuettrumpf J. et al., Blood 2005). These results suggest that in vitro and in vivo expression of biologically-active VKCPs outside the liver may be limited by the host cell post-translational modification machinery. Here, we performed a systematic study to determine the expression profiles of the vitamin K cycle and furin endoprotease genes in human liver and muscle, compared to the mouse. We also established these profiles in two hemophilic dogs, given the extensive use of this animal model in gene-based hemophilia therapies. RNA from liver and skeletal muscle was used as a template for reverse transcription and the subsequent relative quantification of the GGCX, VKORc1, NQO1, and FURIN genes by qPCR in each tissue using a housekeeping reporter gene. For this, a variety of housekeeping genes were investigated in all three species to identify ones with similar transcript levels in both liver and muscle tissue. We identified the housekeeping genes HPRT1, beta actin, and 18s rRNA as equivalently expressed in the liver and skeletal muscle of human, mouse, and dog, respectively. The relative mRNA transcript quantification of the vitamin K cycle genes in humans showed that the transcript levels of GGCX were similar in liver and muscle. In contrast, both VKORc1 and NQO1 were under-expressed in muscle vs. liver (69.5 ± 4.9% and 67.8 ± 12.5%, respectively, P<0.01). In the mouse, VKORc1 transcript levels in the muscle were reduced to 73.8 ± 9.9% vs. liver (P<0.05), while GGCX and NQO1 exhibited similar transcript levels in both tissues. In the dog, we observed a dramatic reduction in VKORc1 and GGCX transcript levels in the muscle vs. liver (11.8 ± 4.2% and 29.5 ± 15.8%, respectively, P<0.01). Surprisingly, NQO1 transcript levels were 253.8 ± 156.7% higher in muscle than liver (P<0.05). Lastly, in all three species tested, transcript levels for FURIN were similar in both muscle and liver. Our results indicate that VKORc1, a key enzyme in the vitamin K cycle, is consistently under-expressed in the skeletal muscle of humans as well as in mice and hemophilic dogs. In contrast, FURIN transcripts are similarly abundant in the liver and muscle of all three species tested. These suggest that the vitamin K cycle but not propeptide processing by furin can be a limiting factor in the secretion of biologically active muscle-expressed VKCPs. As a result, our observations provide (1) a plausible explanation for the inverse relationship between specific activity and Factor IX expression levels in mice following Factor IX gene transfer, and (2) further support for the mouse and dog as useful models for therapies that depend on the muscle-derived expression of VKCPs. Disclosures No relevant conflicts of interest to declare.

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